Dissipation of the heat that results from electronic components operating inside the box of a piece of electronic equipment (television decoder etc.), leads to the temperature that exists inside the box increasing, and thus to increasing the temperature of the box itself.
The increase in the temperature of the box is problematic since the box must not present a temperature that might inconvenience or injure a user as a result of making contact with the box. Concerning those outside portions of a box of a piece of electronic equipment of the decoder type that are not intended to be held or touched by the user on a continuous basis, the maximum acceptable temperature is conventionally 95° C. when said portions are made of plastics material, and 70° C. when said portions are made of metal.
In addition, the increase in the temperature that exists inside the box is problematic because of the impact it has on the electronic components inside the box.
Most electronic components are sensitive to temperature: a high temperature can have consequences on the performance of components, on the failure rate of components, on the integrity of component packages, etc.
The maximum admissible temperature inside a box of electronic equipment of the decoder type is conventionally 90° C.
A first solution is available to the designers of electronic cards that encounter such a temperature problem. This first solution consists in using specific components that are capable of operating for longer at higher temperatures. The use of such specific components is often very expensive since it requires either designing components that are dedicated to the application in question, or else selecting components after performing additional tests concerning thermal qualification. Furthermore, this first solution does not solve the problem of increasing the temperature of the box itself.
A second solution, which is less expensive, and which makes it possible to reduce both the temperature of the box and also the temperature inside the box, consists in improving the discharge of heat from the inside of the box, generally by having recourse to forced ventilation in channels arranged inside the box of the equipment. Such forced ventilation nevertheless presents numerous drawbacks, including increasing the overall size of the equipment, increasing its electricity consumption, increasing the noise it produces when in operation, and possibly leading to the introduction of dust that might degrade the performance of the ventilation. It should also be observed that the short lifetime of fans or blowers in a hot environment can lead to premature failure of the equipment.